Feed finger



S. B. MARTIN FEED FINGER Jul 27, 1937.

Filed NOV. 23, 1936 D SW 6.

1, (Ittornegs Patented July 27, 1937 I pairs srnrs ernr 5 Claims.

My invention relates to improvements in feed fingers'for feeding barstock in hand or automatic screw machines or thelike.

An object of the present invention is to provide a positive, yetstructurally simple means for intermittently feeding rod or barstockinto the path of a tool.

' A further object resides in providinga self releasing stock grippingmember which is so constructed that centrifugal force automaticallyoperates the member to grip the stock when the rotating feed tube ismoved in one direction, but which will release its grip on the stockwhen the tube is at rest or moves in an opposite direction.

Another object of the invention is .to provide a stock gripping meanscomprising an annulus which is movable relatively to the stock when oneof the side walls of the annulus is in a sub- 'stantially verticalplane, but which. grips the stock when another of its walls approachesthe vertical.

.A still further object of the invention is to provide a. feed fingerwith means for intermittently gripping the stock passing therethroughwherein said. means includes a normally loose annulus within :the pushertube and is adapted to shift its position with respect to the tube andstock upon rotation of the tube whereby to grip the stock as the tube ismoved axially in one direction to feed the stock for a cuttingoperation.

Another object is to provide such a gripping device which may bereleased upon a reversal of movement of the tube.

Other objects and advantages of my invention will become more apparentfrom the following description of an embodiment thereof, reference beingmade to the accompanying drawing in which like reference characters areemployed to designate like partsthroughout the same.

Inthe drawing: I

Figure l is a longitudinal section through a feed finger for screwmachines showing my invention in use and the gripping annulus freelyresting on the stock, as when the tube is at rest or when the tube isretracted in the direction of the arrow Figure 2 is a View similar tothat of Figure l, but shows the annulus gripping the stock as the feedtube rotates and moves forwardly in the direction of the arrow to feedthe stock for-. ward.

Figure, 3 is a section taken on line 33 of Figure 2, and,

Figure 4 is a perspective view of the gripping annulus. i

Referring to the drawing in detail which illustrates one form of myinvention, the feed or pusher tube is indicated at l.; 'The'outer end ofthe tube is counterbored for a portion 'of its length at 2 to readilyand-removably receive the gripping annulus the bushing land theretaining'member 5. The retaining member is in the form of a splitresilient ring which is seated in it may be acted upon bya tool in theusual manner,

By my invention Ihave provided means which depends upon centrifugalforcewand/or axial movement of the tube for its operation-J This ameanssincludes-an annulus or ring-pf hardened metal, the side or transversewalls of which preferably lie in intersecting planes. Thus it will beseen that the thickness of the ring at certain diametrically oppositepoint will be at a maximum on one side and at a minimum at the oppositeside.

When the ring is assembled in the tube, the side wall ll) normally liesin a vertical plane while the opposite wall ll lies in a planeintersecting the vertical and the annulus loosely encircles the stock asshown in Figure 1. Thus the bar stock has freedom of movement axially inthe tube I and the annulus, as when the tube is at rest or is moved tothe left in Figure 1. However, when the tube and annulus are rotated,the centrifugal forces set up in the annulus will tend to shift theheavy side of the annulus or ring outwardly to the position shown inFigure 2 and the ring is thus tilted slightly to the right, there beingbut a small annular clearance between the ring and the stock. When thering is in this position, one edge lZalong its lower or thinner portionmay be thrust into contact with the outer surface of the stock and theedge i l will be lowered to gripping engagement with the stock and, asthe tube moves forward to the right, the inner wall or shoulder it ofthe counterbore engages the thicker portion of the annulus 3 at the highpoint ifi'thereof causing the edge M of the annulus at the opposite sideof te thicker portion to bite into the stock surface in grippingrelation.

As long as the pusher tube 6 moves forward, the said edges l2 and M ofthe annulus will firmly grip the stock at substantially diametricallyopposite points on its circumference.

It will be noted that with the parts in the position shown in Figure 2,the annulus or ring engages the shoulder I3 of the tube at only the highpoint as at l5 when the tube is rotated and pushed forward. In thismanner the grip of the annulus or the stock is maintained even when thespeed of rotation of the stock is less than that of the tube such aswhen the forward end of the stock engages the usual bar stop forwardlyof the tube.

However, when the tube is moved in an opposite direction and the wall I3is disengaged from the annulus, the bushing l will engage the oppositeside of the annulus at ill and thus release its grip on the stock, theannulus assuming the position shown in Figure 1. After the tube reachesits limit of motion in this direction, the parts are again in positionto repeat the operation and again move the stock forward.

While my invention is extremely simple, it is very effective in use andis materially inexpensive to manufacture.

With my invention it will be evident that the bar stock can be removedwith very little difficulty and effort and such removal does not requireany disassembling of the machine itself. Furthermore, the pusher annulusor ring is always in position to grip the bar stock and to feed itforwardly without slipping. Another advantage resides in the ability, bythis construction, to use stock having a diameter very closelyapproaching that of the inside of the tube. I have found it possible touse stock having a diameter within one-eighth inch of the inside tubediameter.

Various changes in the details of construction and arrangement of partsmay be made without departing from the spirit of my invention or thescope of the appended claims.

I claim:

1. The combination with a stock feed tube for screw machines, of a stockgripping device within the tube, said gripping device including anannulus having a portion of greater cross sectional area than any otherportion thereof and responsive to the centrifugal forces set up byrotation of the tube, to automatically grip the stock during an axialmovement of the tube in one direction.

2. The combination with a stock feed tube for screw machines,-of a stockgripping device within the tube and operable upon rotation of the tubeto automatically grip the stock, said gripping device comprising anannulus having a maximum thickness at one point and a minimum thicknessat a diametrically opposed point.

3. The combination with a stock feed tube for screw machines, of a stockgripping device within the tube and operable upon rotation of the tubeto automatically grip the stock, a removable retaining member carriedwithin the tube, said tube having an annular internal-groove near itsend and a resilient keeper ring removably seated in said groove, saidgripping device including an annulus having a weighted portion and astock gripping edge within said weighted portion.

4. A gripping member for intermittently gripping the bar stock in a feedtube of a screw machine, comprising an annulus the side walls of whichlie in intersecting planes.

5. The combination with a stock feed tube,

of a stock gripping tube having a portion counterbored inwardly from itsend to receive a stock gripping ring, of a stock gripping ring withinthe tube, said ring having a portion of greater cross sectional areathan any other portion of T the ring, said ring being responsive to thecentrifugal forces set up by rotation of the tube to automatically gripthe stock during an axial movement of the said tube in one direction,the wall of said counterbored portion forming a shoulder with theinternal wall of the gripping tube, said shoulder being adapted toengage said ring near its greater cross sectional area and thereby tiltthe ring into gripping engagement with the stock.

STODDARD B. MARTIN.

